The Arizona Department of Water Resources has an excellent program to monitor a somewhat unique geologic hazard – land subsidence. Caused by compaction of valley sediments in areas of declining groundwater table, it can create significant problems for infrastructure such as drainage facilities, flood control works, and gravity flow utilities such as sewer lines. It can also induce a secondary geologic hazard, earth fissures. The ADWR has been using InSAR data supplemented with GPS surveying and other data since 1997 to monitor a number of land subsidence areas in Arizona. This is the first of what I presume will be a series of comprehensive reports on their program. [Source: Read the PDF report from the ADWR. Image: ADWR Land Subsidence Page]
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SR 87 Landslide Coverage and Update
Back in March of 2008 there was a landslide that closed SR 87 in between Phoenix, Arizona and Payson. It’s been of great interest to me since it is in my state and affected a highway. I was hoping my firm (NCS Consultants, LLC) might be asked to work on the remediation through our on-call contract but it didn’t happen. Its probably for the best, it sounds like it’s been a troublesome geotechnical engineering problem. Fast forward to last week, and the slide area was in the news again because the slope is still moving and apparently causing some additional deformation of the roadway. (Photo by ADOT)
I had heard about this a while ago through our ADOT contacts, but I make it a policy not to take advantage of my contacts through my day job for GeoPrac.net content (not without permission anyway). So I didn’t want to blog about it until it hit the mainstream media. Last week, the Arizona State Geologist blogged about the SR 87 slide moving again, as did Ken through his AEG Arizona Section blog. It was even covered on one of my favorite blogs, Dave’s Landslide Blog. I finally have a chance to wade through these blog posts and some of the reports and videos to present a summary of the situation, available information and offer my own perspective. (More after the break)
Suggested Guidelines for Investigating Land Subsidence and Earth Fissure Hazards in Arizona
From the AZGS Document Repository: These guidelines provide professionals evaluating site-specific conditions in areas known or suspected to be subsiding with a standardized minimum level of investigation for land-subsidence and earth-fissure hazards. The guidelines do […]